Briquetting process



United States Patent 3,414,408 BRIQUETTING PROCESS Walter W.Eichenberger, 2615 W. th St., Erie, Pa. 16505 No Drawing.Continuation-impart of application Ser. No.

309,329, Sept. 16, 1963. This application May 17, 1966,

Ser. No. 550,623

3 Claims. (Cl. 75-214) ABSTRACT OF THE DISCLOSURE Disclosed herein is aprocess of manufacturing briquettes for use in metallurgical products asan alloying agent. The material to be briquetted is enclosed in acontainer made of material that is compatible with the metallurgicalprocess. The containers are provided with holes so that any liquid thatmay be entrained on the material can escape from the holes when thecontainer with the material in it is pressed in a briquetting press. Thecontainers are strong enough to hold the material when briquetted inintegral body.

This is a continuation in part of patent application, Ser. No. 309,329,filed Sept. 16, 1963, now abandoned.

It is common practice to briquette titanium turnings by adding a softmatrix material such as titanium sponge to the turnings and compressingthem in a briquetting press. This requires the utilization of the matrixmaterial and it is sometimes inconvenient and expensive to carry out theprocess.

It has been discovered that by putting the titanium turnings in a cansuch as an aluminum can having sufiicient strength to hold the briquettetogether after pressing and compressing the can in a briquetting press,such compression causes the can to hold its shape and a perfectbriquette results.

When cans made of aluminum are used, the aluminum can filled withtitanium and titanium alloy turnings is compatible with the alloys. Thealuminum forms part of a common alloy which is six percent aluminum,four percent vanadium, and ninety percent titanium.

The container is not only given a permanent set during the briquettingoperation but it is work-hardened during the process so that it holdsthe briquette in shape, thus eliminating the necessity of a binder inthe titanium.

Certain high alloy turnings and borings and most of the SAE 300 and 400series of stainless steels are exceedingly difiicult to briquette in theas-is condition because of the high strengths of these materials whichis further increased even higher by the fact that these turnings andborings are work hardened in the machining process and sometimes, due tohigh machining speeds and feeds they are even air quenched. In manycases, the only way that these superalloy turnings and borings can bebriquetted is by annealing them first. But, annealing is expensive and,unless the annealing is done in a controlled or inert atmosphere, lossof value of the alloys contained can occur through oxidation. Onetheoretical aspect of briquettability of a material is that thebriquetting pressure exerted on the material being briquetted (usuallyrated in tons p.s.i.) should be great enough to permanently deform thematerial thus giving it a permanent set. In the case of thesesuperalloys and the stainless grades, this would mean that unitpressures of higher than 50 tons p.s.i. on the material would have to beused in order to make coherent briquettes. This can be done, but it thencalls for expensive high tonnage rated hydraulic presses. The reason forwanting to briquette these materials in the first place is to be able toremelt them for the primary ice purpose of recovery of the costly alloycontent, i.e. nickel, chromium, cobalt, tungsten, molybdenum, vanadium,titanium, zirconium, tantalum, etc. If these superalloy turnings andborings are charged for remelting into any type of furnace except avacuum furnace, there occurs a considerable oxidation loss due to thehigh amount of surface presented by these borings and turnings to thefurnace atmosphere. By briquetting, these turnings and borings arecompacted into a dense mass which melts much as would a solid heavymass. During melting, there is a normal formation of an oxide film orcrust completely surrounding the mass being melted. Once formed, thisoxide film or crust acts as a protective layer preventing furtheroxidation of the metal surrounded by that film or crust. As theindividual pieces in the furnace melt, they coalesce with the moltenunoxidized metal forming the bath while the oxide film or crust formsthe slag which further protects the bath metal from further oxidationloss. This is why it is beneficial to briquette turnings and borings.

One other benefit of briquettin is that it provides easier and fastercharging and also faster melting to have briquettes instead ofuncompacted, loose turnings and borings.

The idea of using this can method of briquetting provides an economicalmethod of briquetting the superalloy turnings and borings by having thecan original container act as an external binder to make a coherentcompact. It is possible to briquette these superalloy turnings andborings by mixing a binder with them and then briquetting at ordinarybriquetting pressures, but the use of an admixed binder always createsthe problem of contamination of the metal by the chemical constituentsof the binder. The composition of the can used in this can method mustbe compatible with the chemistry of the metal being briquetted andsubsequently remelted. Most of these superalloys have iron (Fe) as oneof their components and the addition of additional iron (Fe) from thematerial of the can used is not significant enough to cause thisadditional (Fe) to be considered as a contaminant. Also, where the tinplate of the can is considered as a contaminant, even though the tinwill volatilize and not enter wholly into the melt, the cans used can beof unplated black steel to eliminate any possibility of tin pick-up inthe melt. Further, the can used need not be of steel at all; it may bemade of nickel sheet or strip, aluminum, titanium, etc., anything thatis compatible with the contained turnings and borings. Also, the canused should be of sufiicient thickness, for example, .025" to .010, sothat it does act as a binder (external) in the finished can. However,even thin sheet or strip makes a satisfactory final product becauseduring the briquetting of the can, the can itself is compressed anddeformed permanently and actually work hardened which strengthens thefinal can. The external binder, which is the compressed and deformed cancontainer, being of a lower melting point than the contained turningsand borings, will melt first and, as it melts, some of it becomesoxidized and this external melting and partial oxidation of the canforms a protective layer surrounding the contained turnings and borings.By the time the outside can layer has melted, the inside contents of theturnings and borings have been heated sufficiently so that they areannealed or softened. Thus, any possible sprin-giness of the containedturnings and borings is rendered non-harmful. If the external binder isof a material of a higher melting point than the contained material,this offers no problem since then the contained material will beprotected from oxidation by the higher melting point can, but themelting points of the can container and the contained material should befairly close to each other.

This can method can also be used in making an alloy addition to a moltenmetal, such as liquid steel, for example. This is an altogetherdifferent application than the melting operation previously covered. Itis becoming more popular these days, due to development of rapid meltingoperations, such as B.O. F. furnace, oxygen lanced open hearth furnace,etc., to add alloying agents to the ladle as the furnace is being tappedrather than to the bath metal in the furnace after it has been refinedor worked to the desired end point. The reason for adding alloys to theladle is that this method is faster and better alloy recovery isobtained this way. When alloy additions, in particular, ferromanganese,ferrosilicon, ferrochrome, are added to the ladle in the lump form,there is always the possibility of segregation occurring due to theincomplete melting and distribution of these lumps of the variousferroalloys.

There is far less chance of segregation occurring if these ferroalloysare added to the bath metal in the furnace since it is usual practice tohold the furnace on heat for a time after making the ferroalloyadditions in order to insure their complete melting. As the heat istapped into the ladle, mixing occurs which further minimizes thepossibility of segregation; but there is a higher loss of the alloycomponent due to increased oxidation loss. If the ferroalloys which areto be added are added to the ladle or to the tapping stream as fines inorder to insure that they melt quickly, there is a considerable loss ofthese fines by the mechanical elevation of the fines with the hot aircurrent which is present as the hot metal, approximately 3000Fahrenheit, is tapped into the ladle. This phenomenon can be called aconvection current loss. The fines are carried away to a considerableextent by this convection of hot air. By taking these ferroalloys asfines and putting them into a can, they can now be added to the ladle orto the tapping stream in the same manner as a lump. Thus, they arecarried into the ladle metal as a lump, but once the can is surroundedby the liquid molten metal, a thermal shock occurs causing the can topop open sending its contents of fines into the ladle metal. Thus,maximum efficiency of the fines can be obtained.

The third application of the disclosed method is totally different fromthe second (alloy addition) purpose but allied to the first purpose(melting). It is the briquetting of excessively wet (any type of liquid,such as water, mineral, or synthetic oil, etc.) borings (cast-ironborings, in particular) or turnings. When attempting to briquette suchwet materials, especially if the borings and turnings are fineparticles, the liquid content is trapped within the briquette and thenet effect is that you are attempting to compress a liquid. 'If thematerial being briquetted is coarse, a considerable portion of theliquid content may be squeezed out during the briquetting process, butsome of it will always remain.

This liquid problem becomes more acute when dealing with fine powders,filter cakes, etc. Further, if the liquid present is an oil type ofliquid, this oil will act as a lubricant between the grains or particlesof the material being briquetted and will result in a weak briquettewhich cannot be handled mechanically without excessive breakage.Borings, turnings and fines are referred to herein as swarf.

In order to briquette such wet materials, without having to first drythem by some preliminary means, the can method disclosed is used with aslight variation. After the can is filled with the material to bebriquetted, the ends and body of the can are punctured with small pinholes. The can may be punctured with these small pin holes before beingfilled with the material to be briquetted. Either before or afterfilling is satisfactory. Then the can is briquetted. After beingbriquetted, the liquid contained in the material is forced (by theinternal stress of compaction) out of these pin holes. It weeps out ofthese pin holes. Without the external can binder, the same weeping wouldoccur momentarily at the instant that the briquette is removed orstripped from the briquetting die, but there also would occur at thesame moment a slight expansion of the briquette which causes it to actas a sponge, pulling the liquid back into the briquette. The externalcan binder prohibits this re-expansion of the briquette from happening.Therefore, there is only one way for the liquid to go, out of the pinholes in the can.

A 4th application is for the manufacture of symmetrical parts, as inpowder metallurgy, a flywheel may be made by putting the can ofmaterials in a die of proper shape, and compressing same.

The advantages in using the disclosed method are as follows:

(a) Lower than normal briquetting pressures can be used since the canacts as an external binder.

(b) The wear on the briquetting tools is lessened since the abrasivesurface of the material being briquetted does not contact thebriquetting tools. The can makes the contact.

(c) Because lower than normal briquetting pressures can be used, theproductivity of the press is increased.

((1) Because lower than normal briquetting pressures can be used, pressmaintenance cost is lower.

(e) Cleaner press operation all around is provided.

It is, accordingly, an object of the present invention to provide animproved briquetting process.

Another object of the invention is to provide an improved briquette.

A further object of the invention is to provide a briquette which issimple in structure, economical to manufacture, and efficient for itspurpose.

Another object is to provide a briquette made from wet material heldtogether by a perforated can.

The above objects and others which may be later referred to, togetherwith others apparent to those skilled in the art, may be attained bycarrying out the invention in the manner hereinafter described indetail.

To carry out the process disclosed herein, the titanium turnings arefirst crushed to compact them before they are put into the container.The container with its contents is then put in a briquetting press andpressed. Cans three inches in diameter to six inches in diameter havebeen found to be suitable for containers for use in this operation.These sizes are stated for purposes of example only. Any convenient sizeof container can be used.

Examples of the process disclosed herein are as follows:

EXAMPLE A 1.-crush titanium turnings to reduce the particle size2.provide aluminum cans of approximately one quart volume and .010"thick 3.fill said cans with said turnings 4.compress the can andturnings in a briquette press.

EXAMPLE B 1.crush titanium turnings 2.provide a steel can .015" thick3.-fill the can with said turnings 4.compress the can and turnings in abriquetting press.

EXAMPLE C l.-provide cast iron borings wet with a liquid 2.provide a canof a metallurgically compatible material having relatively small holestherein having sufiicient strength to hold said borings in briquetteform when pressed 3.-fill said cans with said wet borings 4.compresssaid borings in a briquetting press.

EXAMPLE D 1.provide sponge borings 2.provide a can 3.-fill said can withsaid borings 4.provide a die of the shape of an article of manufacture5.-place the can in the die and press to the shape of the article.

EXAMPLE E 1.-provide sponge iron borings 2.provide a can having smallholes therein 3.-fill said can with wet borings 4.-provide a die of theshape of an article of manufacture 5.-place the can in the die and pressto the shape of the article.

This process can also be carried out on stainless steel turnings of theSAE 300 series; i.e., 18-8 stainless steel. It is well known thataluminum, stainless steel, and many other metals harden and obtainresiliency when coldworked.- Cold-working characteristics which enablethe metals to harden and obtain resiliency have to do with loss ofductility as opposed to elasticity and obtaining resiliency has to dowith an increase in resiliency, Thus, the can will tend to hold theshape into which it is compressed.

The foregoing specification sets forth the invention in its preferredpractical forms but the method described is capable of modificationwithin a range of equivalents without departing from the invention whichis to be understood is broadly novel as is commensurate with theappended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined 'as follows:

1.'A process of briquetting comprising placing swarf wet, with a liquidin a container:

said container being made of bendable material and having sufiicientstrength and rigidity to retain a shape into which it is bent,

compressing said container with said swarf therein to a sizesubstantially less than the uncompressed size of said container in thetools of a briquetting press, thereby forming an integral briquette heldtogether by said container,

said container having perforations therein whereby said liquid in saidswarf escapes when said swarf is pressed.

2. The process recited in claim 1 wherein:

said container is made of a material having suflicient strength to holdsaid swarf in substantially the same shape to which it is pressed -bysaid briquetting press and tools.

3. The process recited in claim 2 wherein:

said material is at least ten one thousandths of an inch thick.

References Cited UNITED STATES PATENTS 2,725,288 11/1955 Dodds 75-2262,783,504 3/1957 Hamjian 75-214 X 2,792,302 5/1957 Mott 75-214 2,943,9337/1960 Lenhart 75-214 3,050,386 8/1962 Von Dohren 75-222 X 3,269,826 8/1966 Bu-mgarner 29-420 X 3,071,463 6/1963 Hausner 75-213 X FOREIGNPATENTS 689,758 6/ 1964 Canada. 758,545 10/ 1956 Great Britain. 925,1425/ 1963 Great Britain.

BENJAMIN R. PADGETT, Primary Examiner.

A. J. STEINER, Assistant Examiner.

